Motor-controller



C. T. HENDERSON.

MOTOR CONTROLLER. APPLICATION HLED JUNE 29. IBM.

Patented May 11,1920.

3 Sl iEETS-SHEET l.

C. T. HENDERSON. MOTOR CONTROLLER.

APPUCATION FILED JUNE 29. 19144 Patented May, 11, 1920.

3 SHEETS-SHEET 2- c. T. HENDERSON.

MOTOR CONTROLLER. APPLICATION FILED JUNE 29, 19M.

Patented May 11, 1920.

3 SHEETS-SHEET 3.

STATES PATENT OFFICE.

m mvrs nnmmnsomor MILWAUKEE, wrsconsm, ASSIGNOR 'ro THE cornea MFG. 00.,or MILWAUKEE, WISCONSIN, a .conronArIoN or WISCONSIN.

uo'ron-conrnonrnn.

Specification of Letters Patent.

Application filed June 29, 1914. Serial No. 847,974,

To all whom it may concern:

Be it known that I, CLARK T. HENDER- SON a citizen of the United Statesresiding at ll'I Li ilwaukee in the county of ilwaukee and State ofWisconsin, have invented new and useful Improvements inMotor-Controllers, of which the following is a full, clear, concise, andexact description, reference being had to the accompanying drawingforming a part of this specification.

his invention relates to improvements in motor controllers.

The invention has among its objects to provide a controller for electricmotors o erating under varying loads, which Wlll automatically tend tomaintain the controlled motor at a given speed notwithstanding)variations in its load. I

ther objects and advantages of the invention will hereinafter a pear.

In the accompanying rawings several embodiments of the invention havebeen diagrammatically illustrated and the same will now be described. I

Figure 1 shows a controller applied to a D. 0. motor;

Fig. 2 shows a modified form of controller also applied to a D. C.motor; and,

Fig. 3 shows acontroller appliedto an A. C. motor.

Referring first to Fig. 1 the same shows a main controlled motor 1governed by a rheostat 2 operated -by a reversible pilot motor 3. Thepilot motor 3 is overned by electromagnetic reversing switc es 5 and 6responsive to reverse operation of a polarized'relay 7. The relay 7, aswill hereinafter appear, is connected in a Wheatstone bridge, includingthe armature of motor 1, and is ada ted to operate upon variations inspeed 0 said motor and in a direction corresponding to .the character ofsuch speed variations. Operation of the rela in turn causes acorresponding operation 0 the rheostat 2 to rectify the speed variationsof the motor 1. x

The motor 1 is shown as of the shunt type, being provided with anarmature A and a shunt field winding F. The rheostat 2 is in serieswiththe armature A and varies the speed of the motor byincreasing ordecreasin the resistance in the armature circuit. l s will beunderstood, operation of the rheostat to increase the resistance 1n thearmature circuit slows down the motor,

while reverse operation of the rheostat to decrease the resistanceaccelerates the motor. Under normal speed conditions the rheostat standsin an intermediate position whereby it may be operated to rectify.either positive or negative speed variations.

The rheostat is schematically illustrated as of thecross head type,havlng a traveling resistance varying element 8 operated by a screwshaft 9'driven by the pilot motor 3. The pilot motor 3 is shown as ofthe shunt type being provided with an armature a and a shunt fieldwinding f, said motor having its armature operative y connected to thescrew shaft 9 through suitable gearing 10.

The reversing switches 5 and 6 are provided with operating windings 5"and 6 respectively and each has two operative positions. Whendeenergized the switches 5 and 6 bridge down contacts 5' and 6respectively and when energized bridge up contacts 5 and 6 respectively.As Wlll hereinafter appear, the switches 5 and 6 are energizedselectively to start the pilot motor in opposite directions and whenboth switches are deenergized the same. establish a dynamic brakingcircuit across the terminals of the pilot motor armature.

The polarized relay 7 has an armature 7 to be attracted in oppositedirections in accordance with the polarization of said relay. Thisarmature cooperates with contacts 11 and 12 to act as a selector for thereversing switches 5 and 6. The relay also has a second armature 7 whichis attracted in the same manner when the relay is energized irrespectiveof its polarization. This armature coacts with contacts 13 to completethe energizing circuit of the switch selected by the armature 7". Thus,both armatures must be attracted to complete circuit for either of thereversing. switches, the armature 7 acting only as a selector and thearmature 7 acting to make and break circuit. The armature 7 b may be setto respond and drop out at any predetermined current values to determinethe duration of energization of the reversing ,switches, while thearmature 7*, need only be actuated upon reversal of the polarity of therelay.

To provide the aforesaid Wheatstone bridge connections the armature ofthe main motor 1 and its rheostat 2 are paralleled by a suitableresistance R and the winding of Patented May, 1920. i

to conductor; 18- and by conducton22 to ad ustable tap 14 of-resistanee-R.

l 15 in! relay-7 is connected on one side to a point between thearmature A. and rheostat 2 and on itsother side to. an adjustable tap llof the resistance R.

Thus if the main motor 1 be adjusted by the rheostat 2 or other means,to operate at theldesired speed under normal load and the connectionbetween the relay winding and resistance R be adjusted to. balance thebridge, the relay 7 will be inert and will render the rheostat- 2quiescent. Should, l1owever,-the speed of the motor 1 vary theheatsto-ne bridge would become unbalanced, effecting energization of therelay 7 with a polarizationcorresponding tothe character of the speedvariation. This in turn would effect operation of the rheostat 2 in adirection to rectify the speed variation and upon accomplishment of thisthe relay-would again become-inert thereby rendering the rheostatquiescent.

' The circuit connections will now be more specifically described: Thefield of main motor 1'- isconnected by conductors 15- and 16 to supplylines L, L respectively. The armature of motor 1 is connected-byconductor '17 to line L, and by conductor 18 throu' h-rheostat 2 to lineL. The resistance" is connected by conductor 19 to line L and byconductor 20 to line L. Thewinding of relay 7 is connected by conductor21 the The field f of the pilot motor is connected by conductor'23 toline-L and by conductor 24: to line L. The armature of the pilotmotor-is normally connectedin a closedloop extending from the right handterminal thereof by conductor 25 through the down contacts 6 and 5ofswitches'fi and=5= by conductor26 to the left hand terminal of themotor armature. Thus whenever the armature of the pilot motorisdisconnected from the supply circuit said motor will act as-a dynamicbrake and quickly come to rest. Upon response-of switch- 5 the armaturecircuit of the pilot motor is closed from conductor 23 by conductor 27to conductor 27"ithrough theup contacts 5 of switch 5,

by conductor; 26 through the armature a from left to r1ght,-by conductor25 through the down contacts 6 oi"- switch 6, by conductor-23 to line L.Upon response of switch 6 the circuit of the motor armature is-clos'edfrom conductor 27 by conductor 27" through the up contacts 6 0% switch6,

by conductor-25 through the armature a from right to left, by conductor23 through the 'down contacts 5 of switch 5, by condtictorQB. toline L.

WVith the armature'7 of the polarized relay in engagement with contact11 and with; the armature 7 in; engagement with contacts 13, circuitisgclosed from conductor c5 emmengress winding-"5* esswaea 5-,: by

conductor 29 through the armature 7 by conductor 30 through the armature7", by conductors 31 and 20 to line L. On the other hand, when thearmature 7 engages contact 12 circuit is completed from conductor 27through the winding 6 of switch 6, by conductor 32 through armature 7 toline L, as already traced.

Referring to thecontroller sliown in Fig. 2, the same is precisely likethat shown in Fig. 1 except in the Wheatstone bridge formation. In thisinstance two motors 33and 34.- are provided in lieu of the resistance R.Both of these motors are of the shunt type, each being provided with anarmature a and a shunt field winding 7. v The armatures are connected inseries across the lines L, L and form-with the main motor armature A,rheostat 2 and relay 7 a Wheatstone bridge, said relay being connectedat a point between thearmatures a. The field windings of the two motorsare connected across the lines L, L through a. rheostat- 35: and arethus adjustable to enable regulation oil the C. E. M. F. ofi-the twomotors-to balance the Wheatstone bridge under normal speed conditions.As will be understood, the motors 33 and 34 afteradjustment there; ofoperate at constant speed whereby the Wheatstone bridge willbecomeunbalanced uponvariations in the speed of the main motor withconsequent response of the relay 7 and motor operated rheosbat 2 asheneinbefore set forth.

The circuit of the field windingof motor 3 extends from line L byconductor 36 through said winding, by conductor-37 to one side of therheostat 35, by conductor 38 to line L. The-circuit of the field'windingof motor 34 extends from conductor 36 by conductor 39 through saidwinding, bycondoctor 40 to the other side-of the rheostat 35 and thenceby conductor 38 to line- L. The rheostat 35, as will be observed, actsoppositely onthe two field windings; that is, cutting out resistance incircuitwithyone upon inserting resistancein cireuitwithrthe other,whereby the desired regulatlon'may be readily obtained.

Referring now to Fig. 3 the some shows a three-phase alternating currentmotor 40 having a stator S and a-rotor R. The-stator of the motor issupplied with current a three-phase alternating current-circuit: 41, 42and 43, while the rotor is connected a rheostat 44 similar to that shownin Figs. 1 and-2-butmodified for-the A. C; motor.

The rheostat 44:, as in the f mer in stances,- is operated by a D. C.pilot motor 3 supplied with current from lines L-and L and governed byreversing switohes5 and 6 and a polarized relay Tsimilar to thosealready described.

The winding of the polarized relay 7 in this-instance commuted 'incincuit: with of the main motor while the armature It of generator 46 isdriven by a constant speed alternating current motor 48 operating uponpower from the alternating'current source.

The arrangement is such that at normal speed of the main motor 40 theoutput of the generator 46 equals that of the generator 47 thusrendering the polarized relay inert. ()n

the other hand, any variation in the speed of the motor causes theoutput of the generator 47 to either exceed or fall below that of thegenerator 46 thereby energizing relay '7 and adjusting its polarityaccording to which generator predominates; Thus this arrangement effectssubstantially the same results as the VVheatstone bridge arrangementheretofore described. 7

As illustrated the output of the generator 46 may be balanced withrespect to that of the generator 47 at normal speed of the main motor bya rheostat 49 in series with the field winding f of said generator 46.As will be understood, as the resistance in the field circuit of thegenerator 46 is-increased its output is decreased, and conversely, whenthe resistance is decreased its output isincreased.

What I claim as new and desire to secure by Letters Patent is 1. Thecombination with a motor operating under varying loads, ofelectro-responsive speed regulating means having a plurality of circuitsfor control thereof to selectively increase or decrease the speed of'said motor, a relay having a winding and two armatures, one of saidarmatures being polarized and movable in opposite directions underreverse current conditions in said winding and the other being attractedand released at predetermined values of such current, said formerarmature in its attracted positions cooperating with said latterarmature in its attracted position to close the circuits of said speedregulating means selectively but subject to interruption upon release ofsaid latter armature and means whereby said relay is energized uponvariations in the speed of said main motor from a given value andwhereby the direction' of current through said relay is varied inaccordance with the character of speed variation.

- 2. The combination with a motor operating'under varying loads, of avariable-resistance for controlling said motor, a reversible pilot motorfor regulating said resistance, a pair of reversing switches forcontrolling said pilot motor. and for establishing dynamic brakingconnections therefor, a relay having a winding and two armatures, one ofsaid armatures being polarized and movable in opposite directions underreverse current conditions in said winding and the other being attractedand released at predetermined values of such current, said formerarmature in its attracted positions cooperating with said latterarmature in its attracted position to energize said reversing switchesselectively but subject to interruption upon release of said latterarmature, ergized upon variations in speed of said main motor from agiven value and whereby the dirction of current through said relay isvaried in accordance with the character of speed variation In witnesswhereof I have hereunto subnesses. Y

- CLARK TRAVIS HENDERSON.

Witnesses:

Tum BAST,

L. A. WATSON.

scribed my name in the presence of two witand means whereby saidrelay'is en-

